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Saturday, December 9, 2017

Signal Quality

I've read in the late 20s QSTs of the need to lightly load a self excited oscillator-transmitter (such as many of us use in the Bruce Kelley) in order to have a nice sounding signal. See Ross Hull concluded that any self-excited oscillator should be loaded to only about half power in order to produce at acceptable signal.

How bad do I sound? Might I rate one of those notices from an OO? When I try to listen to my own signal I'm always overloading the receiver and my signal sounds really bad. Instead I called upon my good friend KC0P who lives about 3 miles from me to listen to me and record what he hears.

Here are three snippets from that QSO using my PP 210s TNT transmitter:

- 3565KHz at 4 watts into a low endfed wire:
Click here
- 3565KHz at 8 watts into a low endfed wire:
Click here
- 7115KHz at 8 watts into a 32' vertical with two radials:
Click here

This really pointed out some weaknesses and strong points of my '29 station. First, this station really is more stable and sounds much better on 80 rather than 40. Next, upping the power on 80 from 4 to 8 watts does make a difference in quality but that difference is not real noticeable.  Finally, pushing this transmitter/antenna to 8 watts on 40 produces a noticeably bad signal. For tonight I'll run 8 watts on 80. I'll have some '29 character but not enough to rate an OO notice. On 40 I'll back off to 4 watts while limiting operating to the late evening. Next week I want to try different power levels and antennas on 40 to see how much things can be improved.

Friday, December 1, 2017

AWA Bruce Kelley 1929 QSO Party

Coming up in a little over a week is the AWA Bruce Kelley 1929 QSO Party. See .

My 2017 "BK" station is built around a   TNT transmitter using 210s in push-pull.  With it I'll use a two tube regen and/or Elecraft KX3 depending on band conditions.

In the front left of my BK operating position is a small table-top rack holding the two receivers plus an audio output transformer connected to a battery powered amplified speaker. Like many early receiver designs my regen has B+ flowing through the headphones. The external output audio transformer makes it safe to use and allows connecting to my amplified speaker. The regen B+ supply is off to the left. I use a power supply built from an Antique Electronics Supply kit. Sitting on the ledge behind the receivers is a regulated high voltage supply. This provides B+ for my transmitter. The TNT transmitter is sensitive to B+ voltage swings. This regulated supply helps control the "whoop". Next to the power supply is a Simpson Wavemeter. This allows me to easily get my transmitter in the band. Exact frequency setting of both the transmitter (and the regen) is done using my KX3 as a frequency monitor. Next is my TNT transmitter. This one is fairly stable and produces a nice note on 40 and 80. I can see why QST featured it in 1930. To the right of the transmitter is a plate current meter. This year BK is limiting input power to 25 watts and power is part of the QSO exchange. This meter is needed for accurate reporting. The wooden box on the far right is my filament supply. It provides both 7.5 volts to the transmitter and 2.5 volts to the regen receiver. On top of the filament supply is a QRP watt meter. This is handy for setting up the transmitter for maximum output. The switch on the table switches the antenna between transmitter and receiver. The key is a Kent Straight Key used for several years by my mentor/step-father K5CF (SK). Optional equipment includes a good cup of coffee, useful while trying to make those late night contacts with the east and west coasts.

In the backyard are my winter 80/40 mtr vertical and 95' inverted L antennas.

Counting down to the 2017 AWA BK